//
//  main.c
//  1
//
//  Created by 顿耀伍 on 2019/10/17.
//  Copyright © 2019 顿耀伍. All rights reserved.
//

#include <stdio.h>
int Find_Max_Crossing_SubArray(int A[], int low, int mid, int high)
{
   int left_sum = -0xff;
   int sum = 0;
   for (int i = mid; i >= low; i --)
   {
      sum += A[i];
      if (sum >left_sum)
      {
         left_sum = sum;
      }
   }
   int right_sum = -0xff;
   sum = 0;
   for (int j = mid + 1; j <= high; j ++)
   {
      sum += A[j];
      if (sum > right_sum)
      {
         right_sum = sum;
      }
   }
   return left_sum + right_sum;
}
 
int Find_Maximum_SubArray(int A[], int low, int high)
{
   int left_sum, right_sum, cross_sum;
   if (high == low)
   {
      return A[low];
   }
   else
   {
      int mid = (low + high) / 2;
      left_sum = Find_Maximum_SubArray(A, low, mid);
      right_sum = Find_Maximum_SubArray(A, mid + 1, high);
      cross_sum = Find_Max_Crossing_SubArray(A, low, mid, high);
      if (left_sum >= right_sum && left_sum >= cross_sum)
      {
         return left_sum;
      }
      else if (right_sum >= left_sum && right_sum >= cross_sum)
      {
         return right_sum;
      }
      else
      {
         return cross_sum;
      }
   }
}
int main()
{
    int A[100];
    int n;
    printf("请输入数组的个数:");
    scanf("%d",&n);
    printf("请输入数组的数：");
    for (int i = 0; i < n; i ++)
    {
       scanf("%d",&A[i]);
    }
    printf("最大子序列的和为：%d\n",Find_Maximum_SubArray(A, 0, n - 1));
    return 0;
}
